Fluid injection device

ABSTRACT

A fluid injection device includes: a pulse generation section that includes a fluid chamber whose volume is changeable, and an inlet flow passage and an outlet flow passage that are connected to the fluid chamber; a first connection flow passage connected to the outlet flow passage, having an end portion; a second connection flow passage connected to the inlet flow passage; a fluid injection opening formed at the end portion of the first connection flow passage, having a diameter smaller than the diameter of the outlet flow passage; a connection flow passage tube including the first connection flow passage and having rigidity adequate to transmit pulses of fluid flowing from the fluid chamber to the fluid injection opening; and a pressure generation section that supplies fluid to the inlet flow passage.

CROSS-REFERENCE TO RELATED APPLICATION

This is a Continuation of application Ser. No. 13/675,640 filed Nov. 13,2012, which is a Continuation of application Ser. No. 13/019,575 filedFeb. 2, 2011 which is a Continuation of application Ser. No. 11/902,766filed Sep. 25, 2007. The disclosure of the prior applications is herebyincorporated by reference herein in its entirety.

This application claims priority from Japanese Patent Application No.2006-261114, filed on Sep. 26, 2006, the contents of which areincorporated herein by reference.

BACKGROUND

1. Technical Field

The present invention relates to a fluid injection device. Morespecifically, the present invention relates to a fluid injection deviceof simple construction that injects stable and strong pulses of fluid.

2. Related Art

Conventional fluid injection device as disclosed in the JapaneseUnexamined Patent Application, First Publication No. 2005-152127, forexample, is well known as a fluid injection device for dissecting orcutting out biopsy tissues.

This fluid injection device includes a micro-pump, a connection flowpassage, and a connection tube.

The micro-pump changes the volume of the pump chamber and discharges thefluid.

The outlet flow passage of the micro-pump is connected to one end of theconnection flow passage, and an opening (nozzle) made smaller than thediameter of the outlet flow passage is formed at another end of theconnection flow passage.

The connection tube has a rigidity that is adequate to transmit thepulses of the fluid flowing from the micro-pump in which the connectionflow passage to the opening is formed.

The fluid flows in this fluid injection device by repetitive pulse wavetrains and pauses, and is injected at high speed from the opening.

In the Japanese Unexamined Patent Application, First Publication No.2005-307743, the art of providing a piston pump and a pump primingdevice on the side of the outlet flow passage of the micro-pumpconfigured as mentioned above, is disclosed.

According to this art, the priming operation is performed at start whenfluid has not entered the micro-pump, and the air in the pump chamber iscompressed and removed after the start of operation.

According to Japanese Unexamined Patent Application, First PublicationNo. 2005-152127, pulsating fluid can be injected at high speed and canbe easily controlled.

While the ability to dissect tissues during surgery, for example, ishigh, the quantity of injection of pulsating fluid was low, and fluidrarely accumulated in the surgical field.

Consequently, visibility was enhanced and the scattering of tissues waseffectively prevented.

This micro-pump required priming operation and elimination of airbubbles in the pump chamber at the start of operation based on theoperating characteristics, and a construction with installation of thepump priming device as disclosed in the Japanese Unexamined PatentApplication, First Publication No. 2005-307743, was proposed.

However, even if a pump priming device is installed, the priming deviceis disconnected and removed after start, and when air bubbles aregenerated in the pump chamber, the drive operation may become unstable.

Also, in the micro-pump according to the Japanese Unexamined PatentApplications, First Publication No. 2005-152127 and First PublicationNo. 2005-307743, the inertance on the outlet flow passage side is setgreater than the inertance on the inlet flow passage side; thus, a checkvalve was installed on the inlet flow passage side to prevent back flowof the fluid.

This check valve is extremely small, and its washability is poor. Also,the check valve may not be able to maintain adequate performance forlong period use or repetitive use.

SUMMARY

An advantage of an aspect of the invention is to provide a fluidinjection device in which it is possible to realize a simpleconstruction having high reliability, to eliminate degradation inperformance due to accumulation of air bubbles during operation, and itis not necessary a priming device.

An aspect of the invention provides a fluid injection device of theinvention including: a pulse generation section that includes a fluidchamber whose volume is changeable, and an inlet flow passage and anoutlet flow passage that are connected to the fluid chamber; a firstconnection flow passage connected to the outlet flow passage, having anend portion; a second connection flow passage connected to the inletflow passage; a fluid injection opening formed at the end portion of thefirst connection flow passage, having a diameter smaller than thediameter of the outlet flow passage; a connection flow passage tubeincluding the first connection flow passage and having rigidity adequateto transmit pulses of fluid flowing from the fluid chamber to the fluidinjection opening; and a pressure generation section that supplies fluidto the inlet flow passage.

As the pressure generation section, a pump discharging fluid at constantpressure may be used, for example.

According to this invention, the fluid is supplied to the inlet flowpassage at a constant pressure from the pressure generation section.Even if the drive of the pulse generation section is in the stopcondition, fluid is supplied to the inlet flow passage and the fluidchamber. Therefore, priming operation is not required, and the initialoperation can be started.

Moreover, the fluid can be injected at high speed because fluid isinjected from a fluid injection opening which has been made smaller thanthe diameter of the outlet flow passage.

Furthermore, since the connection flow passage tube has adequaterigidity to transmit the pulses of the fluid flowing from the fluidchamber to the opening, the propagation of fluid pressure from the pulsegeneration section is not obstructed, and the desired pulse flow can beinjected.

It is preferable that, in the fluid injection device of the aspect ofthe invention, the inertance of the inlet flow passage be set greaterthan the inertance of the outlet flow passage.

In this structure, by driving the pulse generation section, the pulseflow with inflow rate of fluid greater than that of the pulse flow fromthe inlet flow passage to the fluid chamber is generated in the outletflow passage. The fluid in the pulsed state can be discharged into theconnection flow passage tube.

Consequently, there is no need to install a check valve on the inletflow passage side, as in the Japanese Unexamined Patent Application,First Publication No. 2005-152127, the construction of the pulsegeneration section becomes simpler, internal parts can be easilycleaned, and the concern about durability because of using a check valvecan also be eliminated.

If the inertance of both the inlet flow passage and the outlet flowpassage is set adequately great, and if the volume of the fluid chamberis abruptly reduced, then the pressure in the fluid chamber steeplyincreases.

Thus, a pulse flow which is greater than that of the outlet flow passagecan be generated.

It is preferable that, in the fluid injection device of the aspect ofthe invention, the pulse generation section include a volume varyingsection for varying the volume of the fluid chamber, and the volumevarying section include a piezoelectric element that expands orcompresses the fluid chamber, and a diaphragm.

If a piezoelectric element is used as the volume varying section, thestructure can be simplified, and as a result the pulse generationsection can be made smaller.

The maximum frequency of change in volume of the fluid chamber can beset at greater than or equal to 1 kHz, which is ideal for injection ofpulsed flow at high speed and at short repetitive periods.

It is preferable that the fluid injection device of the aspect of theinvention further include: a swirl flow generation section generatingswirl flow of fluid around an axis of the fluid chamber. In thisstructure, the fluid chamber has a substantial rotating body shape, andincludes an inner peripheral wall having a first end and a second end, asealing surface sealing the first end of the inner peripheral wall, anda diaphragm sealing the second end of the inner peripheral wall. Also,in this structure, the outlet flow passage is formed at a portion whichis closer to the axis of the substantial rotating body shape.

The rotating body shape may be selected from cylindrical shape, conicalshape, hemispherical shape, or the like.

By generating a swirl flow in the fluid in the fluid chamber using theswirl flow generation section, the fluid is pushed toward the fluidchamber in the circumferential direction by centrifugal force. The airbubbles included in the fluid near the axis of the substantial rotatingbody shape accumulate at the center of the swirl flow. These air bubblescan be removed from the outlet flow passage formed at a portion which iscloser to the axis of the substantial rotating body shape.

As a result, the reduction in pressure amplitude due to the existence ofair bubbles in the fluid chamber can be prevented. Also, the pulsegeneration section can be driven stably and continuously.

It is preferable that, in the fluid injection device of the aspect ofthe invention, the swirl flow generation section be formed by the inletflow passage that connects the inner peripheral wall of the fluidchamber in a substantially tangential direction.

In this structure, since the swirl flow generation section is formed bythe inlet flow passage, swirl flow can be generated and there is no needto use a special swirl flow generation section.

The inner peripheral wall of the fluid chamber is equivalent to theouter surface of the substantial rotating body shape.

It is preferable that, in the fluid injection device of the aspect ofthe invention, the inlet flow passage be formed on the peripheral edgeof the fluid chamber.

To form an inlet flow passage in this structure, a groove may be formedon the peripheral edge of the fluid chamber, for example, as the inletflow passage.

Consequently, inlet flow passage may be formed as the swirl flowgeneration section without increasing the number of parts.

It is preferable that, in the fluid injection device of the aspect ofthe invention, the swirl flow generation section be formed by a swirlflow generation plate that includes the inlet flow passage and the innerperipheral wall of the fluid chamber.

By forming the swirl flow generation section by a swirl flow generationplate in this structure, the inlet flow passage and the inner peripheralwall may be easily formed by the pressing process, etching process, orthe like.

Moreover, if various types of swirl flow generation plate havingdifferent cross-sectional areas and lengths of the inlet flow passageare kept ready, then the desired inertance can be selectively set on theinlet flow passage side.

It is preferable that, in the fluid injection device of the aspect ofthe invention, the swirl flow generation plate and the diaphragm bestacked and attached in intimate contact as an integral body.

The swirl flow generation plate is made of thin plate. An opening havingthe inner peripheral wall of the fluid chamber and the inlet flowpassage is formed on the swirl flow generation plate.

The structural strength to resist high pressure addition within thefluid chamber is likely to be inadequate. In this structure, by makingthe plate integral with the diaphragm, adequate structural strength canbe obtained.

Another advantage is that handling is easy during assembly.

It is preferable that the fluid injection device of the aspect of theinvention further include: a reinforcing plate that has an opening whosediameter is substantially equal to the diameter of the fluid chamber,and that is formed between the sealing surface on which the inlet flowpassage is formed or the swirl flow generation plate, and the diaphragm.

The inlet flow passage and an opening that forms inner peripheral wallof fluid chamber are formed in the swirl flow generation plate.

In this case, the opening and inlet flow passage merge into a mergedportion, which is in the shape of a notch.

Since the diaphragm takes the periphery of the opening as the drivesupport point, stress concentration occurs in the merged portion.

However, by providing the reinforcing plate, the diaphragm takes theperiphery of the opening of the reinforcing plate as the support point.Thus, stress concentration does not occur easily, and the durability ofthe diaphragm can be enhanced.

It is preferable that, in the fluid injection device of the aspect ofthe invention, the swirl flow generation plate and the reinforcing platebe stacked and attached in intimate contact with each other as anintegral body.

In this structure, the swirl flow generation plate can be reinforced,and handling during assembly becomes easy.

It is preferable that, in the fluid injection device of the aspect ofthe invention, the diaphragm and the reinforcing plate be stacked andattached in intimate contact with each other as an integral body.

In this structure, the swirl flow generation plate can be indirectlyreinforced, and handling during assembly becomes easy.

It is preferable that the fluid injection device of the aspect of theinvention further include: a fluid basin that be formed at theconnection between the second connection flow passage on the inlet sidesupplying fluid to the inlet flow passage from the pressure generationsection and the inlet flow passage, that collects fluid.

The direction of flow of fluid and the cross-sectional area of the flowpassage change at the connection of the second connection flow passageon the inlet side and the inlet flow passage. The characteristics of thesecond connection flow passage on the inlet side are considered toaffect the characteristics of the inlet flow passage.

By installing a fluid basin at the connection, the velocity head in thesecond connection flow passage on the inlet side becomes extremelysmall; thus the influence on the inlet flow passage due to the secondconnection flow passage on the inlet side can be inhibited.

It is preferable that, in the fluid injection device of the aspect ofthe invention, the inlet flow passage be formed by a tubular member thatpasses through the fluid chamber and an exterior of the pulse generationsection.

If the inlet flow passage is formed by a tubular member, thecross-sectional shape of the flow passage can be made circular, and theresistance elements in the flow passage can be reduced.

The inside diameter and length of the tubular member can be easily set.Moreover, the cross-sectional area of the inlet flow passage and thelength of the flow passage can be easily set to match the inertancesetting on the inlet flow passage side.

It is preferable that the fluid injection device of the aspect of theinvention further include: a ring-shaped packing separately disposed ata position in the circumferential direction of the diaphragm.

The diaphragm is a member that seals a part of the fluid chamber.

As mentioned above, since the internal parts of the fluid chamber is athigh pressure, fluid may leak at the connection of the diaphragm.

If fluid leaks from the fluid chamber, the pressure does not rise to thedesired level.

By providing a packing, the fluid leakage can be prevented, and the riseof pressure in the fluid chamber is not hindered.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an explanatory schematic diagram of a configuration of a fluidinjection device of a first embodiment of the invention.

FIG. 2 is a cross-sectional view of a configuration of a pulsegeneration section of the first embodiment of the invention.

FIG. 3 is a plan view of an inlet flow passage of the first embodimentof the invention.

FIG. 4 is a plan view of a swirl flow generation plate of a secondembodiment of the invention.

FIG. 5 is a cross-sectional view of the pulse generation section inwhich the swirl flow generation plate is assembled of the secondembodiment of the invention.

FIG. 6 is a plan view of a diaphragm connected to the swirl flowgeneration plate of a third embodiment of the invention.

FIG. 7 is a cross-section view taken along the line A-A shown in FIG. 6.

FIG. 8A is a plan view showing the connected state of the reinforcingplate and the swirl flow generation plate of a fourth embodiment of theinvention.

FIG. 8B is a cross-sectional view taken along the line B-B shown in FIG.8A.

FIG. 9 is a cross-sectional view of the pulse generation section of thefourth embodiment of the invention.

FIG. 10 is a cross-sectional view of the pulse generation section of afifth embodiment of the invention taken along the line C-C shown in FIG.11.

FIG. 11 is a plan view showing the condition of the upper case relatedto the fifth embodiment of the invention observed from the lower caseside.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

The embodiments of the invention are described hereafter referring tothe drawings.

FIGS. 1 to 3 show the fluid injection device and the pulse generatingsection related to the first embodiment.

FIGS. 4 and 5 show the pulse generating section related to the secondembodiment.

FIGS. 6 and 7 show the pulse generating section related to the thirdembodiment.

FIGS. 8A, 8B, and 9 show the pulse generating section related to thefourth embodiment.

FIGS. 10 and 11 show the pulse generating section related to the fifthembodiment.

The embodiments described hereafter are detailed examples preferred forthe invention and are subjected to various technically preferredlimitations. The scope of the invention is not limited to theseembodiments unless the limitation on the invention is expressly statedin the description below.

The figures referred to in the description below, are schematicdrawings, and the scale on the vertical axis of members and/or parts maydiffer from the actual scale.

The fluid injection device according to the invention may be used invarious applications such as in drawing using ink and so on, in cleaningdense substances and structural items, and for surgical blades. In theembodiments described below, a fluid injection device that is ideal fordissecting or cutting out biopsy tissue is used as an example in thedescription.

Consequently, the fluid used in the embodiment is water or salinesolution.

First Embodiment

FIG. 1 is an explanatory schematic diagram of the configuration of thefluid injection device related to the first embodiment of the invention.

In FIG. 1, the fluid injection device 1 includes a fluid container 10containing the fluid as the basic configuration, a pump 20 as thepressure generation section, and a pulse generation section 100generating a pulse flow of the fluid supplied from the pump 20.

A slender tubular shaped connection flow passage tube 200 is connectedto the pulse generation section 100.

A nozzle 211 with its flow passage compressed is inserted in the frontend of the connection flow passage tube 200.

The flow of the fluid in the fluid injection device 1 is described belowin a simple manner.

The fluid contained in the fluid container 10 is drawn in by the pump 20through a connection tube 15, and is supplied to the pulse generationsection 100 at constant pressure through a connection tube 25.

As shown in FIG. 2, the pulse generation section 100 includes a fluidchamber 501, and a volume varying section of this fluid chamber 501. Thepulse generation section 100 drives the volume varying section andgenerates pulses, and injects the fluid at high speed through theconnection flow passage tube 200 and the nozzle 211.

Detailed explanations on the pulse generation section 100 are givenlater referring to FIGS. 2 and 3.

The pressure generation section is not limited to pump 20; a liquidtransport bag maintained at a position higher than the pulse generationsection 100 by a stand or the like may be used.

Accordingly, the advantages are: the pump 20 is not necessary, theconfiguration becomes simpler, and disinfection is easy.

The discharge pressure of the pump 20 is set at lower than or equal to0.3 atmosphere (0.03 MPa).

If the liquid transport bag is used, the difference in height of theliquid upper surface of the pulse generation section 100 and the liquidtransport bag becomes the pressure.

If the liquid transport bag is used, it is preferable that thedifference in height be set such that the pressure is in the range of0.1 to 0.15 atmosphere (0.01 to 0.15 MPa).

When performing surgery using the fluid injection device 1, the surgeongrasps the pulse generation section 100.

Consequently, it is preferable that the connection tube 25 from the pump20 to the pulse generation section 100 be as flexible as possible.

For this reason, it is preferable that the tube be flexible and thin,and the fluid in the pulse generation section 100 be at low pressurewithin the pumpable range.

Also, when a fault in the equipment may lead to a major accident, as inbrain surgery, the discharge of fluid at high pressure due to a cut inthe connection tube 25 must be avoided; for this reason also, the fluidmust be at low pressure.

Next, the construction of the pulse generation section 100 according tothe first embodiment is described here.

FIG. 2 is a cross-sectional view of the configuration of the pulsegeneration section 100 of the first embodiment.

As shown FIG. 2, the pulse generation section 100 includes a pulsegenerating device for generating pulse in the fluid. The connection flowpassage tube 200 having a connection flow passage (first connection flowpassage) 201 for discharging fluid is connected to the pulse generationsection 100.

The pulse generation section 100 is joined at the surfaces opposite toan upper case 500 and a lower case 301 respectively. The upper case 500and the lower case 301 are screwed in with four securing screws 600 (notshown in the drawings).

The lower case 301 is a cylindrical member having a collar. A portion ofthe lower case 301 opposite to the upper case 500 is sealed by the baseplate 311.

A piezoelectric element 401 is disposed in the space within the lowercase 301.

The piezoelectric element 401 is a stacked-type piezoelectric elementand constitutes an actuator.

The first end of the piezoelectric element 401 is fixed to diaphragm 400through upper plate 411, and the second end of the piezoelectric element401 is fixed to the upper surface 312 of the base plate 311.

Also, the diaphragm 400 is made of a disc-shaped thin metallic plate.The peripheral edge in the groove 303 of the lower case 301 is fixed inintimate contact with the bottom surface of the groove 303.

When a drive signal is input to the piezoelectric element 401 used asthe volume varying section, the volume of the fluid chamber 501 changesthrough the diaphragm 400 with the extension and shrinkage of thepiezoelectric element 401.

A reinforcing plate 410 made of disc-shaped thin metallic plate havingan opening at the center is stacked and disposed on the upper surface ofthe diaphragm 400.

A groove is formed at the central part of the surface of the upper case500 opposite to the lower case 301. A fluid chamber 501 in the shape ofa rotating body and filled with fluid is made of this groove and thediaphragm 400.

That is, the fluid chamber 501 includes a space enclosed by the sealingsurface 505 of the groove of the upper case 500, the inner peripheralwall 501 a, and the diaphragm 400.

An outlet flow passage tube 510 is formed to protrude from the end faceof the upper case 500 opposite to the lower case 301.

An outlet flow passage 511 is formed at substantially the center of thefluid chamber 501.

The outlet flow passage 511 is a through passage from the fluid chamber501 to the end of the outlet flow passage tube 510.

The connection between the sealing surface 505 and the outlet flowpassage 511 is smoothly rounded to reduce the fluid resistance.

As shown FIG. 2, the fluid chamber 501 described above in the firstembodiment has a substantially cylindrical and sealed shape at the twoends, but when viewed from the side, the surface has no limitation. Asthe shape, conical, trapezoidal or hemispherical may be adopted.

For example, if the connection between the outlet flow passage 511 andthe sealing surface 505 is made in the shape of a funnel, air bubbles inthe fluid chamber 501 mentioned later, can be easily removed.

A connection flow passage tube 200 is connected to the outlet flowpassage 510.

A connection flow passage 201 is formed in the connection flow passagetube 200. The diameter of the connection flow passage 201 is grater thanthe diameter of the outlet flow passage 511.

The thickness of the tubing portion of the connection flow passage tube200 is kept within a range such that the connection flow passage tube200 has adequate rigidity yet does not absorb the pressure pulses of thefluid.

A nozzle 211 attached by insertion to the front end of the connectionflow passage tube 200.

A fluid injection opening 212 is formed in this nozzle 211. Thus, thefluid injection opening 212 is formed at the end portion of theconnection flow passage 201.

The diameter of the fluid injection opening 212 is smaller than thediameter of the connection flow passage 201.

An inlet flow passage tube 502 is formed to protrude from the side faceof the upper case 500. The inlet flow passage tube 502 is inserted intothe connection tube 25. The inlet flow passage tube 502 supplies fluidfrom the pump 20.

A connection flow passage (second connection flow passage) 504 is formedon the side of the inlet flow passage in the inlet flow passage tube502.

An inlet flow passage 503 is connected with the connection flow passage504.

The inlet flow passage 503 is formed in a groove shape in the peripheraledge of the sealing surface 505 of the fluid chamber 501, and isconnected with the fluid chamber 501.

At a position which is separated from the diaphragm 400 in thecircumferential direction, and on the connection surface between theupper case 500 and the lower case 301, a packing box 304 is formed onthe side of the lower case 301 and a packing box 506 is formed on theside of the upper case 500, and a ring-shaped packing 450 is attached inthe space formed by the packing boxes 304 and 506.

When assembling the upper case 500 and the lower case 301, theperipheral edge of the diaphragm 400 and the peripheral edge of thereinforcing plate 410 are brought into close contact by the bottomsurface of the groove 303 of the lower case 301 and the peripheral edgeof the sealing surface 505 of the upper case 500.

In this case, the packing 450 is pressed by the upper case 500 and thelower case 301, and fluid leakage from the fluid chamber 501 isprevented.

When the pressure inside the fluid chamber 501 increases to a highpressure above 30 atmospheres (3 MPa) when fluid is discharged, a smallamount of fluid could leak in the connections of the diaphragm 400,reinforcing plate 410, upper case 500, lower case 301, respectively, butthis leak is prevented by the packing 450.

When packing 450 is disposed as shown in FIG. 2, the pressure of fluidthat leaks at high pressure from the fluid chamber 501 compresses thepacking 450, and the walls in the packing box 304 and 506 are pressedwith a strong force; thus, the leakage of fluid can be more firmlyprevented.

As a result, the rise in high pressure in the fluid chamber 501 can bemaintained during the operation.

Next, the inlet flow passage 503 formed in the upper case 500 isdescribed in further detail referring to the drawings.

FIG. 3 is a plan view of the inlet flow passage 503, and indicates thestate when the upper case 500 is viewed from the side of the connectingface with the lower case 301.

The inlet flow passage 503 in FIG. 3 is formed in the shape of aperipheral edge groove of the sealing surface 505 of the upper case 500.

The inlet flow passage 503 connects with the fluid chamber 501 at thefirst end of the inlet flow passage 503. The inlet flow passage 503connects with the connection flow passage 504 at the second end of theinlet flow passage 503.

A fluid basin 507 is formed at the connection between the inlet flowpassage 503 and the connection flow passage 504.

The fluid resistance is reduced by smoothly rounding the connectionbetween the fluid basin 507 and the inlet flow passage 503.

The inlet flow passage 503 is connected with the fluid chamber 501 inthe substantially tangential direction to the inner peripheral wall 501a of the fluid chamber 501.

As shown in FIG. 1, the fluid supplied at constant pressure from thepump 20 flows along the inner peripheral wall 501 a (direction shown byarrow in FIG. 3), and generates a swirl flow in the fluid chamber 501.

The swirl flow presses against the side of the inner peripheral wall 501a due to centrifugal force because of the swirling motion, and the airbubbles included in the fluid chamber 501 concentrate at the center ofthe swirl flow.

The air bubbles that have collected at the center are removed from theoutlet flow passage 511.

Thus, it is preferable that the outlet flow passage 511 be installednear the center of the swirl flow. It is preferable that the outlet flowpassage 511 be installed at the center of the axis of the rotating shapebody.

Consequently, the inlet flow passage 503 is a swirl flow generationsection in the first embodiment.

In FIG. 3, the inlet flow passage 503 is curved in a plane form.

The inlet flow passage 503 may be connected the fluid chamber 501 in astraight line. In order to obtain the desired inertance in a narrowspace, the inlet flow passage 503 is curved. Because it is necessary tomake the flow passage length of the inlet flow passage 503 long.

As shown in FIG. 2, a reinforcing plate 410 is disposed between thediaphragm 400 and the peripheral edge of the sealing surface 505 inwhich the inlet flow passage 503 is formed.

The reinforcing plate 410 is installed to enhance the durability of thediaphragm 400.

Since a connection opening 509 is formed in notch shape in theconnection between the inlet flow passage 503 and the fluid chamber 501,stress concentration occurs near the connection opening 509 and fatiguefailure may occur, when the diaphragm 400 is driven at a high frequency.

Therefore, a reinforcing plate 410 with a continuous opening and nonotch is disposed so that stress concentration does not occur in thediaphragm 400.

Screw holes 500 a are formed at four locations at the corners of theouter periphery of the upper case 500. The upper case 500 and the lowercase 301 are screwed together and connected at these screw holepositions.

The reinforcing plate 410 and the diaphragm 400 may be connected and maybe stacked fixed together to form an integral body, although thisarrangement is not shown in the drawings.

As fixing structure, adhesive may be used to attach the items, or solidstate diffusion bonding, welding or the like may be used. It ispreferable that the reinforcing plate 410 and the diaphragm 400 be inclose contact at the connecting face.

Next, the operation of the first embodiment is described here referringto FIGS. 1 to 3.

The fluid discharge of the pulse generation section 100 of the firstembodiment is performed according to the difference between theinertance L1 (synthesized inertance L1 may sometimes be called) on theinlet flow passage side and the inertance L2 on the outlet flow passageside (synthesized inertance L2 may sometimes be called).

Inertance is first described below.

The inertance L may be expressed by L=ρ×h/S, where density of fluid isρ, cross-sectional area of flow passage is S, and the length of the flowpassage is h.

If the differential pressure in the flow passage is taken as ΔP, and theflow rate of fluid flowing in the flow passage as Q, then the equationof motion in the flow passage using inertance L may be modified toobtain the relationship ΔP=L×dQ/dt.

That is, the inertance L indicates the influence level on the changewith time of flow rate. The greater the inertance L, the smaller is thechange with time of the flow rate; the smaller the inertance L, thegreater is the change with time of the flow rate.

The synthesized inertance related to parallel connections of a pluralityof flow passages or direct connections of a plurality of flow passageswith varying shapes can be calculated by combining the inertance ofindividual flow passages, similar to parallel connections or directconnections of inductance in an electric circuit.

For the inertance L1 on the inlet flow passage side, since the diameterof the connection flow passage 504 is set adequately greater than thatof the inlet flow passage 503, the inertance L1 can be calculated in therange of the inlet flow passage 503.

In this case, since the connection tube connecting the pump 20 and theinlet flow passage has flexibility, the connection tube may not beconsidered in the calculation of inertance L1.

In case of the inertance L2 on the outlet flow passage side, thediameter of the connection flow passage 201 is much greater than theoutlet flow passage, and the thickness of the tube portion (tube wall)of the connection flow passage tube 200 is small, therefore theinfluence on the inertance L2 is negligible.

Consequently, the inertance L2 on the outlet flow passage side may bereplaced with the inertance of the outlet flow passage 511.

The thickness of the tube wall of the connection flow passage tube 200is such that it has adequate rigidity to transmit the fluid pressure.

In the first embodiment, the length and cross-sectional area of the flowpassage of the inlet flow passage 503, and the length andcross-sectional area of the flow passage of the outlet flow passage 511are set such that the inertance L1 on the side of the inlet flow passagebecomes greater than the inertance L2 on the side of the outlet flowpassage.

Next, the operation of the pulse generation section 100 is describedhere.

Fluid is supplied at constant pressure at all times in the inlet flowpassage 503 by the pump 20.

As the result, when the piezoelectric element 401 does not operate, thefluid flows into the fluid chamber 501 because of the difference in thevalue of the fluid resistance of the entire inlet flow passage and thedischarge pressure of the pump 20.

Here, if the drive signal is input to the piezoelectric element 401, andif the piezoelectric element 401 extends rapidly, the pressure in thefluid chamber 501 rises sharply and reaches several tens of atmospheresif the inertance L1 and L2 on the side of the inlet flow passage andoutlet flow passage are adequately high.

This pressure is much higher than the pressure due to pump 20 applied onthe inlet flow passage 503. Thus, the inflow of fluid to the fluidchamber 501 from the side of the inlet flow passage reduces according tothis pressure, and the outflow from the outlet flow passage 511increases.

Consequently, a check valve installed on the inlet flow passage side, asin the fluid injection device according to the Japanese UnexaminedPatent Application, First Publication No. 2005-152127, is not required.

However, inertance L1 of the inlet flow passage 503 is greater than theinertance L2 of the outlet flow passage 511; therefore, the increase influid discharged from the outlet flow passage is greater than thedecrease in the inflow of the fluid to the fluid chamber 501 from theinlet flow passage 503. So the flow discharge in pulse form is generatedto the connection flow passage 201, that is a pulsed flow is generated.

The pressure variation at the time of this discharge is transmitted towithin the connection flow passage tube 200; that is, fluid is injectedfrom the fluid injection opening 212 of the nozzle 211 at the front end.

Here, since the diameter of the fluid injection opening 212 of thenozzle 211 is smaller than the diameter of the outlet flow passage 511,the fluid is injected at a higher pressure as high speed droplets inpulse form.

On the other hand, the fluid chamber 501 is in a vacuum stateimmediately after rise in pressure because of the mutual interactionbetween the reduction in fluid inflow rate from the inlet flow passage503 and the increase in fluid outflow from the outlet flow passage 511.

As the result, after a fixed period of time, the fluid in the inlet flowpassage 503 returns to the flow toward the fluid chamber 501 at the samespeed as before the action of the piezoelectric element 401 because ofboth pressure of the pump 20 and the vacuum state within the fluidchamber 501.

If the piezoelectric element 401 extends after the flow of fluid in theinlet flow passage 503 is restored, the pulse flow from the nozzle 211can be continued and fluid can be injected.

Next, the action of removal of air bubbles in the fluid chamber 501 isdescribed here.

During the operation of the pulse generation section 100 describedabove, swirl flow occurs in the fluid chamber 501, and the air bubblesincluded in the fluid are discharged outside the outlet flow passage 511immediately. Because the fluid chamber 501 has a substantial rotatingbody shape and includes the inlet flow passage 503 as a swirl flowgeneration section, and also because the outlet flow passage 511 isformed in an open condition near the rotating axis of the substantialrotating body shape.

Accordingly, even during a very small volume change in the fluid chamber501 due to the piezoelectric element 401, pressure variation is nothindered by air bubbles, and adequate rise in pressure can be obtained.

Consequently, according to the first embodiment 1, the initial operationcan be started without priming operation because fluid is supplied tothe inlet flow passage 503 at constant pressure from the pump 20 andbecause fluid is supplied to the inlet flow passage 503 and the fluidchamber 501 even when the drive of the pulse generation section 100 isin the stopped state.

Moreover, the liquid pressure increases above that in the outlet flowpassage 511 since fluid is discharged from the fluid injection opening212, which is smaller than the diameter of the outlet flow passage 511;therefore, high speed fluid injection can be attained.

Furthermore, the connection flow passage tube 200 possesses adequaterigidity to transmit the pulses of the fluid flowing from the fluidchamber 501 to the fluid injection opening 212. Thus, the pressurepropagation of fluid from the pulse generation section 100 is nothindered, and the desired pulse flow can be injected.

Since the inertance of the inlet flow passage 503 is set greater thanthe inertance of the outlet flow passage 511, an increase occurs in theoutlet flow passage 511 in the outflow rate that is greater than thedecrease in the inflow rate of the fluid to the fluid chamber 501 fromthe inlet flow passage 503, and fluid in pulse state can be dischargedinto the connection flow passage tube 200.

Therefore, advantageous effects can be obtained such as: a check valveneed not be installed on the side of the inlet flow passage 503 as inthe Japanese Unexamined Patent Application, First Publication No.2005-152127, the construction of the pulse generation section 100 can besimplified, internal parts can be cleaned easily, and the concern aboutdurability when using a check valve is eliminated.

By setting the inertance of both the inlet flow passage 503 and theoutlet flow passage 511 adequately great, and by abruptly reducing thevolume of the fluid chamber 501, the pressure in the fluid chamber 501can be increased steeply.

The construction can also be simplified by using piezoelectric element401 and diaphragm 400 as the volume varying section, which can result infurther miniaturization of the device.

The maximum frequency of for volume change of the fluid chamber 501 canbe made greater than or equal to 1 kHz, which is ideal for injection athigh speed pulse flow.

By generating swirl flow in the fluid in the fluid chamber 501 by theswirl flow generation section, the fluid presses against the fluidchamber in the circumferential direction because of the centrifugalforce of the fluid, and the air bubbles included in the fluid near theaxis of the substantial rotating body shape become concentrated at thecentral part of the swirl flow, and these air bubbles can be removedfrom the outlet flow passage 511 formed at a portion which is closer tothe axis of the substantial rotating body shape.

As a result, the reduction in pressure amplitude due to accumulation ofair bubbles in the fluid chamber 501 can be prevented, and stableoperation of the pulse generation section 100 can be continued.

Moreover, since the swirl flow generation section is formed by the inletflow passage 503, swirl flow can be generated without using a specialswirl flow generation section.

Also, a groove-shaped inlet flow passage 503 is formed on the peripheraledge of the sealing surface 505 of the fluid chamber 501, an inlet flowpassage 503 can be formed as the swirl flow generation section withoutincreasing the number of parts.

Moreover, since a reinforcing plate 410 is formed on the upper surfaceof the diaphragm 400, and since the diaphragm is driven taking theperiphery of the opening of the reinforcing plate 410 as the supportpoint, stress concentration does not occur easily, and the durability ofthe diaphragm 400 can be enhanced.

If the corners of the joining surface of the reinforcing plate 410 andthe diaphragm 400 are rounded, the stress concentration of the diaphragm400 can be further relaxed.

If the reinforcing plate 410 and the diaphragm 400 are stacked and fixedas an integral body, the assembly of the pulse generation section 100can be improved, and the reinforcement of the peripheral edge of thediaphragm 400 can also be made more effective.

The influence of the inertance of the connection flow passage 504 on theinlet flow passage 503 can be suppressed by providing fluid basin 507for collecting the fluid at the connection of the inlet flow passage 503and the connection flow passage 504 on the inlet side supplying fluidfrom the pump 20.

Moreover, since a ring-shaped packing 450 is separately disposed at aposition in the circumferential direction of the diaphragm 400 on theconnection surface between the upper case 500 and the lower case 301,the leakage of fluid from the fluid chamber 501 is prevented, and thepressure drop in the fluid chamber 501 can also be prevented.

Second Embodiment

Next, the pulse generation section related to the second embodiment ofthe invention is described here referring to the drawings of the same.

The second embodiment has a swirl flow generation plate including theinner peripheral wall of a fluid chamber and inlet flow passage as theswirl flow generation section.

Other than the swirl flow generation section, the construction issimilar to that of the first embodiment described above, so theexplanations are omitted here. The same reference numerals as in thefirst embodiment are attached to the functional members that are thesame in the first embodiment.

FIG. 4 is a plan view of the swirl flow generation plate 550, and FIG. 5is a cross-sectional view of the pulse generation section 100 in whichthe swirl flow generation plate 550 is assembled.

In FIG. 4, the swirl flow generation plate 550 has an opening formed atits central part; however, the peripheral part of this opening has theinner peripheral wall 551 a of the fluid chamber 551 formed therein.

Also, the inlet flow passage 558 is formed as the swirl flow generationsection in the fluid chamber 551, and a fluid basin 557 is formed in thepart connecting the connection flow passage 504 on the inlet side.

The shape of the inlet flow passage 558, fluid basin 557 and innerperipheral wall 551 a conform to the shape of the inlet flow passage503, the fluid basin 507, and the inner peripheral wall 501 a (see FIG.3) described in the first embodiment above.

The swirl flow generation plate 550 may be formed by processing methodssuch as pressing process, etching process, or electric dischargingprocess.

As shown in FIG. 5, the swirl flow generation plate 550 is stacked anddisposed on the upper surface of the diaphragm 400, and is pressed andbrought into contact with the peripheral face of the sealing surface 505of the upper case 500 and the lower case 301.

Consequently, according to second embodiment mentioned above, by formingthe swirl flow generation section by the swirl flow generation plate550, the inlet flow passage 558, the inner peripheral wall 551 a and thefluid basin 557 can be formed by the same manufacturing process; thus,the mutual positional accuracy can be enhanced.

Also, the swirl flow generation plate 550 is a single body, and can beformed by the pressing process, etching process or electric dischargeprocess. The manufacturing method may be arbitrarily selected to suitthe desired size such as flow passage length, width, thickness, andother shape conditions.

Moreover, if a swirl flow generation plate having cross-sectional areaof inlet flow passage and flow passage length of a plurality of types ofpassages are available and by selecting swirl flow generation plate, thedesired inertance of the inlet flow passage can be easily selected.

Third Embodiment

Next, the third embodiment of the invention is described here referringto the drawings.

The third embodiment has a swirl flow generation plate and diaphragmstacked and attached in intimate contact as an integral body.

Other than the swirl flow generation section, the construction issimilar to that of the second embodiment described above, so theexplanations are omitted here. The same reference numerals as in thesecond embodiment are attached to the functional members that are thesame in the second embodiment also.

FIG. 6 is a plan view of the swirl flow generation plate 550 and theconnected diaphragm 400 related to the third embodiment. FIG. 7 is across-section view taken along the line A-A shown in FIG. 6.

The swirl flow generation plate 550 is attached in intimate contact asan integral body with the diaphragm 400 in FIGS. 6 and 7.

The swirl flow generation plate 550 and the diaphragm 400 may beattached to each other by attaching structure such as bonding usingadhesive, by solid state diffusion bonding, welding or the like. It ispreferable that the swirl flow generation plate 550 and the diaphragm400 be in close contact at the connecting face.

According to this third embodiment, the swirl flow generation plate 550is made from a thin plate. An opening that forms the inner peripheralwall 551 a of the fluid chamber 551 and the inlet flow passage 558 isprovided.

Slender peninsular-shaped members are formed in the connection 559 atwhich the opening and the inlet flow passage 558 are connected.

Since the high pressure state and the vacuum state occur repetitively inthe fluid chamber 551, the structural strength of the slenderpeninsular-shaped members mentioned above may be inadequate.

However, adequate structural strength can be obtained by integrating thediaphragm 400 and the swirl flow generation plate 550.

Another advantage is that handling is easy during assembly.

Fourth Embodiment

Next, the fourth embodiment of the invention is described here referringto the drawings.

In the fourth embodiment, an additional reinforcing plate is formed tofurther strengthen the structure of the second embodiment mentionedabove.

Other than the additional reinforcing plate in the swirl flow generationsection, the construction is similar to that of the second embodimentdescribed above, so the explanations are omitted here. The samereference numerals as in the second embodiment are attached to thefunctional members that are the same in the second embodiment also.

FIG. 8A is a plan view of the connected state between the swirl flowgeneration plate 550 and the reinforcing plate 410 related to the fourthembodiment.

FIG. 8B is a cross-sectional view taken along the line B-B shown in FIG.8A.

In FIGS. 8A and 8B, the swirl flow generation plate 550 has a similarshape as that in the second and third embodiments. The reinforcing plate410 has a similar shape as that in the first embodiment. Both membersare stacked, and are attached in intimate contact with each other as anintegral body by fixing structure such as an adhesive, solid statediffusion bonding, welding or the like at the connecting face.

The swirl flow generation plate 550 and the reinforcing plate 410 isassembled in the pulse generation section 100 in the attached andintimate contact state.

FIG. 9 is a cross-sectional view of the assembled state of the joinedswirl flow generation plate 550 and the reinforcing plate 410 in thepulse generation section 100.

In FIG. 9, the swirl flow generation plate 550 and the reinforcing plate410 are disposed in the integrated state on the upper surface of thediaphragm 400.

Also, the swirl flow generation plate 550 and the reinforcing plate 410are pressed and brought into contact with the peripheral face of thesealing surface 505 of the upper case 500 and the lower case 301.

After preparing plate members that constitute the swirl flow generationplate 550 and the reinforcing plate 410, the plate member constitutingthe swirl flow generation plate 550 is joined to the plate memberconstituting the reinforcing plate 410, and the inlet flow passage 558,fluid basin 557 and inner peripheral wall 551 of the swirl flowgeneration plate 550 may be formed by half-etching, and the innerperipheral wall 410 a of the reinforcing plate 410 may be formed byetching.

Even if the diaphragm 400 and reinforcing plate 410 are joined, and theswirl flow generation plate 550 is assembled and constructed as a singlestructure, the diaphragm 400, the reinforcing plate 410 and the swirlflow generation plate 550 may be stacked, and attached in intimatecontact with each other.

Consequently, according to the fourth embodiment mentioned above, bystacking and attaching the swirl flow generation plate 550 and thereinforcing plate 410 in intimate contact with each other to form anintegral body, the swirl flow generation plate 550 can be reinforced,and handling during assembly also becomes easy.

Also, by stacking and attaching the diaphragm 400 and the reinforcingplate 410 as an integral body, or by stacking and attaching thediaphragm 400, the reinforcing plate 410 and the swirl flow generationplate 550 in intimate contact with each other, the effects of theinvention mentioned above work well.

Fifth Embodiment

Next, the pulse generating device related to the fifth embodiment of theinvention is described here referring to the drawings of the same.

According to the fifth embodiment, the inlet flow passage is formed bytubular member that penetrates the fluid chamber and an exterior of thepulse generation section. The construction of the inlet flow passage ismainly described here.

With respect to other functional members, the same reference numerals asin the first embodiment are affixed and described here.

FIG. 10 is a cross-sectional view of the pulse generation section 100related to the fifth embodiment taken along the line C-C shown in FIG.11, while FIG. 11 is a plan view of the upper case 500 as viewed fromthe side of the lower case 301.

In FIGS. 10 and 11, the inlet flow passage tube 520 is to attach byinsertion into the upper case 500 toward the fluid chamber 501.

The inlet flow passage tube 520 is made from a metallic tubular member,penetrates the outside of the upper case 500, and passes through up tothe fluid chamber 501.

Accordingly, the inlet flow passage 521 formed in the inlet flow passagetube 520 connects with the fluid chamber 501.

When the inlet flow passage 521 is configured with the same conditionsfor the pulse generation section 100 and the inertance L1 of the inletside shown in the first embodiment above, the cross-sectional area andthe flow passage length are set the same as for the inlet flow passage503 as shown in FIG. 3.

Here, the construction of attachment by insertion of the inlet flowpassage tube 520 is described.

An insertion hole guide portion for inlet flow passage tube 514 isformed in the upper case 500 into which the inlet flow passage tube 520is attached by insertion.

Inlet flow passage tube insertion holes 512 and 513 are formed in asubstantially perpendicular direction from the surface of this insertionhole guide portion for inlet flow passage tube 514 toward the fluidchamber 501.

Low-melting point silver solder plating is provided on the inlet flowpassage tube 520. After insertion in the inlet flow passage tubeinsertion hole 513, it is heated and fused by the silver solder. Theinlet flow passage tube 520 and the upper case 500 are attached inintimate contact with each other, and the leakage of fluid from thefluid chamber 501 is prevented.

The front end of the inlet flow passage tube 520 is cut such that itdoes not protrude into the fluid chamber 501.

The method of attaching the inlet flow passage tube 520 may be selectedfrom using adhesive, by press-fitting or the like. A method that canresist the pressure in the fluid chamber 501 and that does not generateleakage of fluid is preferable.

The fluid chamber 501 includes a groove formed at the connection of thelower case 301 with the upper case 500. The fluid chamber 501 has asubstantial rotating body shape.

The inlet flow passage 503 is installed in a substantially tangentialdirection with respect to the inner peripheral wall 501 a of the fluidchamber 501 as shown in FIG. 11.

Accordingly, a swirl flow can be generated in the fluid chamber 501.

A connection tube 25 connecting the pump 20 (see FIG. 1) is connected tothe end in the outward direction of the inlet flow passage tube 520.

The end 25 a of the connection tube 25 extends up to the inside of theinlet flow passage tube insertion hole 512. To minimize the clearance inthe radial direction of the end 25 a and the inlet flow passage tubeinsertion hole 512, the inlet flow passage tube 520 can be reinforced.

Although not illustrated, if the part of the inlet flow passage tube 520protruding outside the upper case 500 is bent, the direction ofconnection of the connection tube 25 can be set arbitrarily, and theoperability of the pulse generation section 100 can be improved.

Consequently, according to the fifth embodiment described above, if theinlet flow passage 521 is formed by the inlet flow passage tube 520, thecross-sectional shape of the inlet flow passage 521 can be madecircular, and the resistance elements in the flow passage can bereduced.

Also, the cross-sectional area and the length of the tubular member canbe easily set. Also, if various types of tubular members are kept readybeforehand, the cross-sectional area and the flow passage length of theinlet flow passage 521 can be easily set to match the settings ofinertance on the side of the inlet flow passage 521.

This invention is not limited to the embodiments mentioned above;changes, modifications within the scope of realization of the objects ofthe invention are included.

Consequently, according to the first to the fifth embodiments describedabove, in the fluid injection device, a priming device (primingoperation) is not necessary, performance degradation due to airaccumulating in the fluid chamber during the operation is eliminated,and a simple construction with no check valve and with high reliabilitycan be offered.

What is claimed is:
 1. A fluid injection device comprising: a pulsegeneration section that includes a fluid chamber for generating a pulsedflow, in which pressure inside the fluid chamber increases when thepulsed flow is generated; an inlet flow passage and an outlet flowpassage that are connected to the fluid chamber; and a fluid injectionopening formed at an extension of the outlet flow passage, whereininertance on the inlet flow passage is greater than inertance on theoutlet flow passage.
 2. The fluid injection device according to claim 1,wherein the pressure inside the fluid chamber is configured to be above30 atmospheres when fluid is injected.
 3. The fluid injection deviceaccording to claim 1, wherein the pulse generation section includes avolume varying section for varying the volume of the fluid chamber, andthe volume varying section includes a piezoelectric element that expandsor compresses the fluid chamber, and a diaphragm.
 4. The fluid injectiondevice according to claim 1, further comprising: a reinforcing platethat has an opening whose diameter is substantially equal to thediameter of the fluid chamber, and that is formed between a sealingsurface on which the inlet flow passage is formed and the diaphragm. 5.The fluid injection device according to claim 4, wherein the diaphragmand the reinforcing plate are stacked and attached in intimate contactwith each other as an integral body.
 6. The fluid injection deviceaccording to claim 1, further comprising: a fluid basin that is formedat the connection between the second connection flow passage on theinlet side supplying fluid to the inlet flow passage from the pressuregeneration section and the inlet flow passage, and that collects fluid.7. The fluid injection device according to claim 1, wherein the inletflow passage is formed by a tubular member that passes through the fluidchamber and an exterior of the pulse generation section.
 8. The fluidinjection device according to claim 1, further comprising: a ring-shapedpacking separately disposed at a position in the circumferentialdirection of the diaphragm.
 9. A biological tissue incising devicecomprising the fluid injection device according to claim
 1. 10. Abiological tissue incising device comprising the fluid injection deviceaccording to claim
 2. 11. A biological tissue incising device comprisingthe fluid injection device according to claim 3.